Rapid replication is characteristic of virulence in, among other things, certain bacteria, viruses and malignancies. The inventors have described a quantitative chemistry common to rapid replication in different viruses and organisms. The chemistry of rapid replication described by the inventors is present in a family of conserved small protein sequences related to rapid replication, Replikins. An increase in the concentration of these Replikin sequences encoded in the genome of different strains of influenza virus has been correlated with an increase in the virulence of influenza. A correlation between increased concentrations of Replikin sequences and increased replication and virulence has likewise been observed in a range of viruses and organisms. Replikin sequences offer new targets for developing effective methods of predicting and treating influenza outbreaks. There continues to exist a particular need in the art for methods of predicting viral outbreaks.
Influenza is an acute respiratory illness of global importance. Despite international attempts to control influenza virus outbreaks through vaccination, influenza infections remain an important cause of morbidity and mortality. Worldwide influenza pandemics have occurred at irregular and previously unpredictable intervals throughout history and it is expected that influenza pandemics will continue to occur in the future. The impact of pandemic influenza is substantial in terms of morbidity, mortality and economic cost.
Influenza vaccines remain the most effective defense against influenza virus, but because of the ability of the virus to mutate, and the availability of non-human host reservoirs, it is expected that influenza will remain an emergent or re-emergent infection. Global influenza surveillance indicates that influenza viruses may vary within a country and between countries and continents during an influenza season. Virologic surveillance is of importance in monitoring antigenic shift and drift. Disease surveillance is also important in assessing the impact of epidemics. Both types of information have provided the basis of vaccine composition and use of antivirals. However, there has traditionally been only annual post hoc hematological classification of the increasing number of emerging influenza virus strains, and no specific chemical structure of the viruses was traditionally identified as an indicator of approaching influenza epidemic or pandemic. Until recently, the only basis for annual classification of influenza virus as active, inactive or prevalent in a given year was the activities of the virus hemagglutinin and neuraminidase proteins.
The small peptide structure called Replikins has now been identified within influenza virus proteins and correlated with an increase in virulence. A Replikin sequence is an amino acid sequence of 7 to about 50 amino acids comprising a Replikin motif. A Replikin motif comprises (1) at least one lysine residue located at a first terminus of the motif and at least one lysine residue or at least one histidine residue located at a second terminus of the motif, (2) a first lysine residue located six to ten residues from a second lysine residue; (3) at least one histidine residue; and (4) at least 6% lysine residues. A Replikin sequence may comprise a terminal lysine and may further comprise a terminal lysine or a terminal histidine. A Replikin peptide or Replikin protein is a peptide or protein consisting of a Replikin sequence.
Higher concentrations of Replikin sequences in the genomic code are associated with a variety of infectious agents including HIV, plant viruses, and a range of pathogenic animal and human viruses including flu viruses. Further, the correlation between the concentration of Replikin sequences in viral or organismal proteins and major outbreaks of disease is significant. Replikin sequences generally have been found to be conserved in both intrastrain and interstrain influenza viruses for as long as 89 years based on data going back to the 1917-18 flu pandemic. Concentration of Replikin sequences in viral genomes has been shown to increase prior to strain-specific flu outbreaks.
Within the last century there have been three influenza pandemics, each strain specific: H1N1 in 1918; H2N2 in 1957; and H3N2 in 1968. The inventors have established that prior to each pandemic there was a strain-specific increase in the concentration of Replikin sequences within the strain. The strain-specific increase in Replikin concentration was followed by a decrease in Replikin concentration and several years later a rebound increase in Replikin concentration associated with a strain-specific rebound epidemic. The Replikin algorithm provided the first chemistry that correlated with influenza epidemics and pandemics.
A similar correlation between the outbreaks of H5NI (Bird Flu) between 1997 and 2007 and the concentration of Replikin sequences in the viral proteins during each of those years has been demonstrated. Likewise, a correlation has been established between the global outbreak of SARS coronavirus in 2003 and an increase in the concentration of Replikin sequences in the proteins of coronavirus. In another study, Replikins in two strains of human HIV-1 virus demonstrated that the Replikin concentration in the rapidly replicating strain was six fold greater than that of a slowly replicating strain. No instances of rapid replication have been observed in all the viruses and organisms examined wherein the Replikin concentration did not significantly increase as compared to the Replikin concentration in the dormant state.
The highest concentration of Replikin sequences in an organism or virus that has to date been analyzed and reported is 111 Replikin sequences per 100 amino acids in the extraordinarily-rapidly-replicating parasitic protozoa Plasmodium falciparum (reportedly responsible for 90% of malarial deaths in humans) (herein sometimes referred to as malaria). P. falciparum has been observed to replicate 11,000 times in 48 hours during passage of the parasite from liver to blood in the host.
It has been believed that changes in the activity of different influenza strains are related to random sequence changes in influenza hemagglutinins, which in turn are the products of substitutions effected by one of two poorly understood processes: i) antigenic drift, thought to be due to the accumulation of a series of point mutations in the hemagglutinin molecule, or ii) antigenic shift, in which the changes are so great that genetic reassortment is postulated to occur between the viruses of human and non-human hosts. The data provided by the inventors suggests that change in activity in different influenza strains, rather than being related to non-specific random sequence changes, is based upon, or related to, an increase in concentration of strain-specific Replikins. Data were also examined for insight into which sequence changes were due to “drift” or “shift” and which were due to conservation, storage in “reservoirs,” and reappearance. The data has shown that the epidemic-related increase in Replikin concentration is not due to the duplication of existing Replikins in the hemagglutinin of the emerging strain, but, instead is due to the reappearance of at least one Replikin composition from 1 to up to 59 years after its disappearance, plus (in the A strains only) the emergence of new strain-specific Replikin compositions. See U.S. Pat. No. 7,189,800 issued Mar. 13, 2007 (Tables 3-6).
In monitoring Replikin sequences in influenza virus, the inventors have additionally identified a sub-family of conserved Replikin sequences known as Replikin Scaffolds or Replikin Scaffold sequences. Replikin Scaffolds were initially identified in conserved structures in particularly virulent influenza viruses. Included among these strains were the viruses causing the pandemics of 1918, 1957, 1968 and virulent strains of the H5N1 “bird flu” strain of influenza virus. Analogues of Replikin Scaffold sequences have since been identified in the virulent and rapidly replicating SARS coronavirus. See U.S. Published Application No. 2007/0026009.
Scaffolding of Replikin sequences homologous but not identical to the algorithm of the identified Replikin Scaffold has also been identified in P. falciparum. Replikin scaffolding in general has been related to an increase in Replikin concentrations in pathogenic genomes where it has been identified. In P. falciparum, scaffolding contributes significantly to the very high Replikin concentration noted in the proteins of the protozoa.
There is a need in the art for methods of predicting increases in virulence of influenza prior to outbreaks. There is likewise a need in the art for methods of preventing and treating outbreaks caused by virulent strains of influenza. Because of the annual administration of influenza vaccines and the short period of time when a vaccine can be administered, strategies directed at improving vaccine coverage are of critical importance.